Re: [lwip-users] LLDP Implementation for lwIP

[Amit Ashara]

Hello Sergio,

As I mentioned earlier, the receive part is not the problem (based on the inputs from Simon and going through the lwIP files. It is the transmit path for which the call stack is not clear. Tracing it seems to always bring me to the DHCP or TCP call function.

Regards

Amit

On Wed, Aug 3, 2016 at 2:46 PM, Amit Ashara <address@hidden> wrote:

Hello Simon

I was referring to the following link

http://lwip.wikia.com/wiki/LwIP_Developers_Manual

This implementation is only for a single port device, which connects to a switch/router. While the receive part is clear, it is the transmit path that is not clear.

In the current implementation netif->linkoutput is already mapped to a function which calls the EMAC driver. I checked the call stack and the transmit call comes from the DHCP during IP address acquisition. So it is not clear where do I insert the LLDP frame?

Regards

Amit

On Wed, Aug 3, 2016 at 2:07 PM, address@hidden <address@hidden> wrote:

Amit Ashara wrote:

I would like to develop the Link Layer LLDP stack within lwIP framework.

Cool!

However the developer's manual link is empty.

I have absolutely *no* idea what this means.

Any suggestions where to start?

Implementing LLDP is a bit tricky if you have more than one port, as lwIP sees this as one 'netif' having a single IP address only (but the ports have a MAC address each, used for LLDP at least).

That being said, you'll have to send and receive LLDP packets on every Ethernet port. If you have only one port, send via "netif->linkoutput" and intercept before calling "ethernet_input()". If you have more than one port, it gets more tricky and doesn't really fit the lwIP netif concept:-(

Then, grab lwIP 2.0.0 (RC2 is the current one) and use the MIB-compiler from "contrib/apps/LwipMibCompiler" to implement the LLDP mib(s?) and feed the results of rx parsing into that mib.

I'd be interested in taking a look at the code once it's done!


Simon

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